Encrusting Gorgonian

The Encrusting Gorgonian is ideal for beginners. It’s one of the easiest gorgonians to care for and propagate!

The Encrusting Gorgonian Erythropodium caribaeorum is an attractive, robust gorgonian. It forms a smooth stolon, or mat, that is tan, cream or coffee colored. Fine long tentacles emerge from star-shaped pinholes on the surface, and they are usually cream or light brown but can have a blue or green cast to them. It is a fast growing species, rapidly spreading to encrust all hard surfaces it comes in contact with. Thus the common names Encrusting Gorgonian or Encrusting Polyps.

The Erythropodium genus is easily confused with species from the Briareum genus like the Corky Sea Finger Briareum asbestinum, which is another encrusting type of gorgonian. However there are some distinctions to help identify them. When the tentacles are retracted, the polyps on the Briareum species are housed in raised calyces or bumps on the surface, rather than having a smooth surface like the Erythropodium coral. The Briareum coral can also form short upright extensions, fingers, or lobes arising from the mat. These are mostly absent from the Erythropodium species.

The Encrusting Gorgonian is very easy to care since it’s not picky about lighting or water movement. It is hardy, adaptable, fast growing, and low maintenance. This rapidly spreading gorgonian will cover any hard surface. It is useful as a decorative species to cover rocks, the sides and back of the aquarium, and to hide aquarium equipment such as plastic pipes and overflow boxes. It makes a great beginner’s coral and is a wonderful candidate for those who want to try propagation techniques.

The Erythropodium genus has a symbiotic relationship with the marine algae, zooxanthellae, which they receive some of their nutrients from. Although the Encrusting Gorgonian and its algae will do well with light, this species is less demanding as far as feeding is concerned. It can actually do fine with no feeding as long as it is in a tank with a reasonable amount of suspended detritus and fish load, otherwise it can be fed fine particle foods dispersed into the water.

The Encrusting Gorgonian will reproduce quicker with strong light and current. You may not want them to reproduce too quickly in your tank, however, since they will overgrow any coral they get close to. They are highly aggressive and placement is critical to protect other sessile animals. They can form sweeper tentacles along the edge of their expanding mat. These tentacles pack a potent sting that will kill most stony corals on contact. On the flip side, it’s great in displays with fish inclined to feed on corals, as it is especially noxious and unlikely to be snacked on.

To learn more about these fascinating Octocorals see:
What Are Gorgonians? Types of Gorgonians, Sea Fans and Sea Whips

Habitat: Distribution / Background

The Encrusting Gorgonian Erythropodium caribaeorum was described by Duchassaing and Michelotti in 1860. Another common name this species is known by is Encrusting Polyps.

About the Erythropodium Genus:

The Erythropodium genus was described by Kolliker in 1865. These are encrusting soft corals in the Class Anthozoa, Subclass Octocorallia, and Order Alcyonacea. They are currently classified as a gorgonian under the Suborder Scleraxonia, which have fused sclerites in their core and rind. The Erythropodium genus is further placed in the Anthothelidae family under the Subfamily, Anthothelinae, which consists of 6 genera: Alertigorgia, Anthothela, Briareopsis, Eryhropodium, Tubigorgia, and Victorgorgiaone.

There are about 8 accepted species in the Erythropodium genus including E. astreoide (Studer), E. caribaeorum (Duchassaing & Michelotti, 1860), E. carybaeorum (Kölliker, 1865), E. hicksoni (Utinomi, 1972), E. indica (Thomson & Henderson, 1905), E. marquesarum (Kükenthal, 1919), Incrusting Gorgonian E. polyanthes (Deichmann, 1936), and E. salomonense (Thomson & Mackinnon, 1910). The common names they are known by are Encrusting Gorgonian and Encrusting Polyps.

The classification of gorgonians in general is done by some simple visual clues such as colony size, shape, axis structure, color, polyp placement, and pattern of branches. Getting a little more technical, they also look to see if the polyp is autozooid or siphonozooid. Then there is the more exacting use of chemotaxonomy, used to show the different terpenoids or other chemicals produced by each gorgonian species.

The Erythropodium corals are found in both the Atlantic and Pacific Oceans, although they are more common in the Atlantic. These encrusting gorgonians are commonly seen and not on the IUCN Red List for Endangered Species. They are found at depths between 3 to 100 feet (1 – 30 m) and will inhabit many patch reef areas, c inter tidal areas, and other types of reefs. While they reside in areas of shallow to mid-depth water, the water flow differs in each of the areas ranging from heavy turbulence and strong currents to light tidal flows. They are very aggressive and will grow over any coral, hard surfaces, and even rubble.

About the Encrusting Gorgonian:

The Encrusting Gorgonian E. caribaeorum is found in the Caribbean, Bahamas, and Florida. It inhabits coral reefs and rocky bottoms in water as shallow as 1.5 feet and as deep as 39 feet (0.5 to 12 m). In Carrie Bow Cay, Belize they are found on back reefs and lagoons, reef crests, low spur and groove zones, outer ridge slopes and fore-reef slopes at depths of 82 feet (25 meters). They resided in both clean and turbid waters, strong currents, and light tidal flows.

Encrusting Gorgonians will absorb nutrients from the water column and also obtain nutrients from the marine algae, zooxanthellae, in which they have a symbiotic relationship with. They are very aggressive, encrusting any hard or rubble surface, as well as other corals. Unlike other gorgonians, once a colony breaks away from its parent colony, they no longer recognize the mother colony and will attack and over grow it.

Predators for this genus include several parasitic copepods, Butterflyfish, Parrotfish and snails from the Murex genus. However, these are noxious corals containing natural chlorinated diterpenoid compounds that are strong deterrents to most predation.

Description

The Encrusting Gorgonian forms a smooth mat that can be tan, cream, or toffee colored, often with a reddish underside. Fine long, hair-like tentacles arise out from tiny star shaped holes on the surface. These autozooid polyps are usually cream to light brown. When the polyps are extended from these pale, whitish openings, they give the colony a “hairy” or “furry” appearance. They are generally extended, but they can fully retract into the mat if disturbed. There are some colonies, especially in the Cayman Islands, that have a blue-hue to their thin tentacles, appearing to float over their tan mat.

The mat is only about a half of an inch (1.27 cm) thick. It does not branch upward but can cover large areas, anywhere from about 3 inches to 3 feet (8 – 90 cm) across. This gorgonian is highly aggressive and not picky about what it encrusts. It will grow over any hard surface, including loose rubble and rock, and other corals. It can form long sweeper tentacles along the edge of its expanding mat, especially in strong water movement. These tentacles pack a potent sting that will kill any nearby corals. Life span is unknown.

The Erythropodium genus can resemble species the Briareum genus, like the Corky Sea Finger B. asbestinum, also from the Atlantic. Although they are both encrusting gorgonians, there are differences that can be seen by simple observation. The Erythropodium genus has a a smooth surface with tiny openings that the polyps arise out of. In contrast, the polyps of the Briareum corals reside in raised calyces or bumps on the surface. The Briareum species can also have short upright extensions arising from the mat which are mostly absent from the Erythropodium species.

Difficulty of Care

The Encrusting Gorgonians are perfect for the beginner since they are very hardy and easy to care for. They are one of the most adaptive corals in the wild. They not picky about light and have a high tolerance for both turbidity and a wide range of water movements. Although they are photosynthetic, they need less light than many other corals too. Their tolerance of low light also makes them easier than other photosynthetic gorgonians.

This Gorgonian does fine with no feeding as long as it is in a tank with fish. When comes to water quality, however, if the water has phosphates that will encourage cyanobacteria and algae growth. Strong illumination and vigorous water movement is needed as these gorgonians can be easily overtaken if the water flow is too low.

The Encrusting Gorgonian will also reproduce quicker with strong light and feeding. However, you may not want them to reproduce too quickly in your tank. As their name implies, they are encrusting and will overgrow any coral that they get close to. They can produce sweeper tentacles that pack a strong sting, so placement is critical to protect other sessile animals. Putting a well spaced sand barrier between them and desirable corals may help reduce the risk of spreading. Interestingly, once a colony separates from the mother colony, they will attack each other, so care has to be taken to put space between them as well.

Foods and Feeding

In the wild, Erythropodium corals have developed several feeding strategies. They capture planktonic organisms and microscopic food particles from the water column, and can absorb dissolved organic matter. Unlike a lot of other Gorgonians, the Encrusting Gorgonian has a symbiotic relationship with a marine algae known as zooxanthellae, where they also receive some of their nutrients.

In captivity, the Encrusting Gorgonian does well with no feeding as long as it is in a tank with a reasonable amount of suspended detritus and fish load. Otherwise, they can be fed Artemia nauplii, rotifers, other similar sized plankton like foods, or dissolved frozen food that disperse in the water into fine particles. Stirring the substrate to suspend edible particulates is also helpful. Feeding them on a weekly basis, along with strong light, makes them grow very fast.

Aquarium Care

Stable tank conditions are needed to keep the Encrusting Gorgonian and other members of the Erythropodium genus. Water changes of 10% biweekly or 20% a month is needed, although it is suggested that doing 5% water changes once a week will replenish many of the needed additives.

Iodine, calcium, strontium, and other trace elements can be added to maintain proper levels for good growth. Phosphates should be maintained as close to zero as possible to reduce cyanobacteria and algae growth, and a pH between 8.2 and 8.4.

Aquarium Setup

The Encrusting Gorgonian needs a mature tank that is 10 gallons or more. This coral can cover areas small as 3 inches (8 cm), but can grow up to 3 feet (90 cm), so may need a tank to eventually accommodate this size. They are also great for nano tanks since they do not grow vertically.

Quick Reference Chart
Lighting:
Water Flow:
Temperament:

A typical live rock/reef environment is what is needed for your Encrusting Gorgonian, along with some fish for organic matter production. Lighting can be low to high, but they need at least a moderate water flow. They are highly adaptable, but a strong water flow and bright lighting will encourage the Encrusting Gorgonian to spread. If the water movement is too slow they can be overtaken by cyanobacteria and algae. The water temperature needs to be kept lower than some corals, between 68° and 79°F (20° to 26° C). These Octocorals are an aggressive species and can extend sweeper tentacles, so adequate space should be provided between them and other corals.

The E. caribaeorum will rapidly spread, so should be isolated away from everything. It is helpful to keep the colony on a rock that isn’t connected to any of the other rock work to keep them from spreading and taking over other corals. A sandy substrate is best since this coral will spread onto any hard surface, including rubble and possibly more stationary substrates like crushed coral. Placing them on a “rock island” surrounded by sand will help prevent their spreading to other hard surfaces and onto corals. Stirring the sand will help provide nutrients for them to absorb from the water column.

Social Behaviors

The Encrusting Gorgonian is very aggressive in that it will grow over any surface it touches, although not usually sand. This hardy gorgonian will attack any encroaching coral, even if it is a new separate colony from itself. It can extend sweeper tentacles with a very potent sting, that can often kill another coral on contact. Make sure you isolate your Erythropodium coral on a “rock island” in the sand where it cannot touch the other rock work or any other corals. You may want to put at least 4-6†of sand between it and your rock work or any other coral.

Most fish will not bother this coral, however, Butterflyfish are known to feed on gorgonian polyps or tissue, so keep an eye on them. Some angelfish will also pick at the polyps, but can be housed with them if the angelfish is well fed. Other fish in the tank benefit the Encrusting Gorgonian in that they provide nutrients for the coral with their waste. Avoid the Flamingo Tongue Snails Cyphoma. which are readily available for purchase, since they will eat your gorgonian, and also avoid snails from the Murex genus.

This is the “coral” of choice to add to a tank with known coral eaters since most fish will not bother it. These noxious corals contain natural chlorinated diterpenoid compound which are strong deterrents to most predation. However, Butterflyfish are known gorgonian gorgers so keep an eye on them. Some angelfish will also pick at the polyps, but can be housed with them if the angelfish is well fed. Parrotfish are also predators of the genus. Other fish in the tank benefit the gorgonian, providing nutrients with their fishy waste. Avoid the Flamingo Tongue Snails Cyphoma. which are readily available for purchase, since they may eat your gorgonian, and also avoid snails from the Murex genus.

Sex: Sexual differences

There are no discernible sexual differences.

Breeding / Reproduction

The Erythropodium genus has been propagated in captivity. The Encrusting Gorgonian can reproduce much like the Briareum genus, by spreading and fragmentation of their mat. Once their runner-like mats attach to surrounding rockwork or corals, they will form a new colony. They will separate from the parent colony and no longer recognize each other.

They may also spawn like other gorgonians for sexual reproduction. When ready to spawn the Erythropodium genus is similar to the Rumphella genus in that it will release mature gametes into their digestive system, which is then released up and out through the mouth. After this spawning method, the zygote will develop into planktonic larvae or free floating in open waters. They will form tentacles, septa and a pharynx right before they settle into the reef with the mouth pointing upward.

Propagation in captivity is easy and is usually done with incising. Taking a razor blade or scalpel, cut into the colony 1/2 way. Try to do this in one pass, since multiple cuts will lead to infection. The goal is to keep the colony attached at least 1/2 way for now. They make a lot of mucus, so this helps to keep it from making everything gooey. This also encourages it to grow onto a new surface and is the safest and least intrusive way of helping the colony bud off and increase growth.

Placing the cut colony over loose rubble is a great way to propagate frags, since it has the ability to grow over uneven surfaces. Many reef keepers will use this encrusting gorgonian to cover intake boxes, tubing and back walls of their tanks since they are so easy to grow. Keep separate colonies away from each other since the Erythropodium genus will attack its own offspring once it has been severed. This is another reason to only incise. It keeps everyone happy and connected. Cutting off what you want to sell or give away is fine.

Ailments / Diseases

The Encrusting Gorgonian, as well as the entire Erythropodium genus, is hardy and very easy to care for. However they are susceptible to collecting detritus and to algae and cyanobacteria accumulating on its surface.They can get red band and black band infections that are caused by cyanobacteria. Keeping a moderate and turbulent water flow will help prevent this. If your gorgonian does get a bacterial infection, you can cut off the bad part, and the rest will tend to recover. Freshwater dips can also kill cyanobacteria, and are an effective treatment.

• Black Band Disease (BBD)
  This ailment is characterized by a leading band of black gooey material (mostly algae), which leaves a denuded skeleton behind. The bare skeleton then becomes covered with many species of algae. You can use a needle to lift the black band from the coral skeleton. With a small diameter airline tubing, siphon the black front away, catching any loosened debris as well. If it is not possible to remove all of the black band, you may be able to treat the area directly by applying a small amount of Erythromycin or Chloramphenicol.
• Red Band Disease (RBD)
  As the name “red band” indicates, this ailment is characterized by a brick red or dark brown band. The band is a soft microbial mat which will easily dislodge from the surface of the coral.

The Erythropodium species may also be a food source for Flamingo Tongue Snails Cyphoma spp. and snails from the the Murex genus. It can also be attacked by several parasitic copepods.

Availability

The Encrusting Gorgonian E. caribaeorum is not easy to find at pet shops or online. Typically they are found mislabeled as a Briareum species, and are moderately priced.

References

• Animal-World References: Marine and Reef
• Erythropodium caribaeorum encrusting gorgonian, SeaLifeBase
• Erythropodium caribaeorum (Duchassaing & Michelotti, 1860), WORMS World Registry of Marine Species
• Eric Borneman, Aquarium Corals : Selection, Husbandry, and Natural History , TFH Publications, 2001
• Anthony Calfo, Book of Coral Propagation, Volume 1 Edition 2: Reef Gardening for Aquarists, Reading Trees; 2nd edition, 2007
• Ronald L. Shimek, Guide to Marine Invertebrates: 500+ Essential-to-Know Aquarium Species, Microcosm, 2005
• Julian Spring and J. Charles Delbeek, The Reef Aquarium: A Comprehensive Guide to the Identification and Care of Tropical Marine Invertebrates (Volume 1), Ricordea Publishing, 1994
• Bob Goemans, Encrusting Polyps, Animal Library, Saltwatercorner.com

Featured Image Credit: Erythropodium caribaeorum 01 by Line1 by Liné1, Wikimedia Commons CC SA 3.0 Unported, 2.5 Generic, 2.0 Generic, and 1.0 Generic